is 2 128857 - 1
has 38790 decimal digits
takes 0.000 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-LB016E66897D92719double-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbability
Actual268462.566175.0000 %100000000001234861517029140254,760.287934.0441 %255,222.854083.5110 %
Target2440.000061.3636 %22002000000.00006.3421 %0.000163.8140 %
Difference+24+462.5661+13.6364 %+9999997800+1234861516829140+254,760.2879+27.7020%+255,222.8539+19.6970 %

Known prime factors:
No known factors for M128857

P-1 results:
dateusercompB1B2BSstagefactordigitsbits*GHz-daysFac Prob
2000-11-25ANONYMOUSv4_computers100000025000000--0.00927.858%
2002-06-02ANONYMOUSv4_computers32768327680012--0.00119.440%
2002-07-20ANONYMOUSv4_computers65536655360012--0.00222.033%
2003-02-09ANONYMOUSv4_computers1310721310720030--0.00324.588%
2003-09-29ANONYMOUSv4_computers2621442621440012--0.00627.096%
2011-02-21Budannan100000000200000000012--0.77141.246%
2023-01-17JossManual testing1000000173706132600--45.3748.743%
2023-02-17JossManual testing1000000522803591310--136.550.785%
2023-09-11Oliver Kruse5950X100000000001234861517029140--254,76074.082%


P+1 Factoring results:
dateuseridcompidb1b2startfactorSmoothdigitsbits*ghz-days
2023-04-22masserManual testing50000000405000000027--1.096
2023-04-27masserManual testing50000000255000000012871--0.793
2023-05-04masserManual testing50000000305000000065--0.894


Trial Factoring results:
575859606162636465666768
 BitsFactor
dateuseridcompidfromtofactorbits*digitsGHz-days
1999-09-22ANONYMOUSv4_computers2522530.005
2000-04-19ANONYMOUSv4_computers212540.019
2022-03-07LordJuliusManual testing254255
2000-12-31ANONYMOUSv4_computers212560.074
2002-06-09ANONYMOUSv4_computers212570.149
2016-02-23Mark RoseManual testing2572580.149
2008-12-31Sturle Sundegibus.ifi2582590.298
2009-02-07Sturle Sundegiacco.ifi2592600.596
2012-12-01Richard B. WoodsPuttputt2602611.192
2015-08-14NRManual testing2612622.384
2016-02-28Gordon SpenceManual testing26226422.85
2018-05-14chuenkitManual testing26426529.00
2019-07-15YxinityManual testing26526657.99
2020-02-12Gordon SpenceManual testing266267116.0
2022-05-09404_factor_not_foundManual testing267268232.0


ECM factoring results:
Total ECM effort:127.416 GHz-days
Estimated T-Level:35.764
DigitsB1CompleteFacMiss
2011000354.7250.000%
255000070.7220.000%
3025000011.0820.002%
3510000001.42424.080%
4030000000.15385.824%
45110000000.01498.597%
50440000000.00199.885%


ECM Summary

B1B2factorcurvesGHz-days
5000050000003110.781
250000250000003784.924
2500005000000030.054
10000001000000001,56085.43
1000000200000000513.705
300000030000000019832.53


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
2016-06-01MadPooManual testingB016E66897D927190.000


PRP results:
No PRP results for M128857


CERT results:
No CERT results for M128857


P-1 factor-bounds graph:
B1 = 10000000000, B2 = 1234861517029140 (P-1 stage 2)
B1 = 1000000, B2 = 522803591310 (P-1 stage 2)
B1 = 10000000000 (P-1 stage 1)
B1 = 1000000, B2 = 173706132600 (P-1 stage 2)
B1 = 100000000, B2 = 2000000000 (P-1 stage 2)
B1 = 100000000 (P-1 stage 1)
B1 = 1000000, B2 = 25000000 (P-1 stage 2)
B1 = 262144, B2 = 26214400 (P-1 stage 2)
B1 = 1000000 (P-1 stage 1)
B1 = 131072, B2 = 13107200 (P-1 stage 2)
B1 = 65536, B2 = 6553600 (P-1 stage 2)
B1 = 262144 (P-1 stage 1)
B1 = 32768, B2 = 3276800 (P-1 stage 2)
B1 = 131072 (P-1 stage 1)
B1 = 65536 (P-1 stage 1)
B1 = 32768 (P-1 stage 1)
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TF factor-bounds graph:
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this exponent TF target: 44
TF double-checked to: 67
ECM T-Level=35.76 ~= 102-bit
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Last modified: 2024-03-13T02:15:48+00:00